Field
This invention relates generally to a lifting apparatus and specifically to a rack and roller pinion lift system.
Prior Art
Certain elevators apply a drive mechanism based on a rack and gear system, also referred to as rack and gear elevators. A motor mounted an elevator car drives a gear the teeth of which engage a wave crest type toothed rack (see FIGS. 15-16) secured to a wall of an elevator shaft. Drawbacks of wave crest rack and gear elevators include noise generated when the gear teeth move along the rack and relatively poor ride comfort. For these reasons, rack and gear elevators are typically used in areas when noise and ride comfort are not critical such as the building industry or other industrial applications. For example, a dual rack and gear drive and an integral I-beam rail and rack system can be used in outdoor broadcast towers.
Despite these drawbacks, a rack and gear elevator does not need a drive machine located in an overhead space or a machine room and does not need the expensive redundant pulleys and cables needed to assure backup safety typical of building elevators. However, a strong rack is needed, thus reducing cost savings. Further, a rack and gear elevator does not require a counterweight traveling along the elevator shaft and thus allows a smaller shaft or more passenger space in a given elevator shaft, but uses a large expensive gear and has to have a motor on the elevator carriage that may generate noise passengers would not like. Also the gear and rack engagement is adjacent the elevator and can generate additional noise passengers might not tolerate well in a typical office building. Such noise might accentuate any claustrophobia or other fears many people have of elevators. Rack and gear elevators, thus are not currently typically found in office buildings despite the clear advantage that they require less space than, for example, conventional traction elevators. For these reasons, rack and gear elevators are conventionally not considered suitable for non-industrial uses. I hope to change all that through improvements to both the rack and the gear using some out-of-the-box thinking.